Lumen works on a few MacOS systems, I believe intel based chips and Metal2+ on UE 5.0.2 can run it without major issues. However Nanite is still off the table almost entirely until UE5.1+. Some users have been able to kind of get Nanite working with various hacks on MacOS but it causes some serious artifacting, crashing, etc. That said we are trying to get more MacOS compatibility by 5.1. A thread with many MacOS users tracking it: Lumen & Nanite on MacOS
Pertaining to the water, I can’t replicate the bug itself.